Despite the similar pairing state, an important difference between \(\mathrm {Sr}_{2}\mathrm {Ru}\mathrm {O}_{4}\)  and the cuprates is that at least one other pairing state must be sufficiently close in energy to contribute to the
condensate near strong local strain inhomogeneities. The idea that a second competing superconducting instability is likely present in this material was proposed before both on phenomenological and microscopic grounds [1]}, [2]}, [3]}, [4]}, [5]}.
In distinction to these investigations, the sub-leading instability of our theory does not need to be fine-tuned to have approximately the same \(T_c\)  value as that of the leading \(d\) -wave instability. Moreover, because the dislocation induces strain in all symmetry channels, TRSB occurs independently of the sub-leading state's symmetry—\(s\) -wave or \(g\) -wave.
Finally, in our scenario, TRSB does not correspond to the homogeneous condensation of the second pairing state, but to a collective phenomenon in which the phase windings of the sub-leading pairing wave-function induced near a dislocation phase-lock globally. A direct consequence of the assumption of competing superconducting instabilities is that, in a clean sample, the sub-leading pairing state should lead to a Bardasis-Schrieffer excitation [6]} in the electronic Raman spectrum. Finally, strain engineering of \(\mathrm {Sr}_{2}\mathrm {Ru}\mathrm {O}_{4}\) , e.g. via plastically deformation of the sample, which is known to impact dislocations in other perovskites [7]}, may be used to create and manipulate time-reversal symmetry broken superconducting states.
